A few drunken pointers then sterfane. Don't use a bad belt now because you might be low on expertise in the future. Don't gem armor pen unless you have a really high amount of it from gear or grim toll/mjolnir's runestone. Don't worry about expertise because other people tell you to, worry about it if you find yourself thinking hey! I really dont like how much these mobs are dodging me. Check out [Design: Nightmare Tear]

The break even point between gemming ArP and Agi WAS ~300, but will raise significantly in 3.2.2(read foxglove's post). The best answer to your question, Hakana, is that it depends(idol and ArP proc trinkets mainly).

Use a tool like FbN, Simcraft or Toskk's to determine the point where YOU should switch to ArP from Agi.

Updated first post.

Changed ArP caps:

Hard cap - 1400 (1399.57)
Soft cap Grim Toll - 788
Soft cap Mjolnir - 735


Breakpoint ArP > Agi roughly at 400 ArP.

ITEM ONE
Recommend adding the following line to the Cat DPS Rotation section:

0. Keep up FFF unless you have a good boomkin who knows how important Imp FF is to the raid's damage.

If you have the luxury of always running in an optimized raid comp the point is moot. But for the rest of us it's not. Examples: The boomkin is sick or filling in for the Resto Druid, or it's late in the week, everyone's saved and you end up in the 2nd-string/half-pug 10-man hard mode group that has no boomkin.

Starting a bossfight with FFF before Mangle also slows down your initial aggro-gain for a precious 1.5 seconds. With Cower useless and Vigilance/Hand of Salvation at a premium or not available this is a real concern.

ITEM TWO
Please forgive me for digging up something from two pages ago, but I keep ending up coming back to the same one of Boevis' posts and I see no relevant discussion of this issue anywhere else on this forum:
Admittedly there a few static fights in today's endgame raiding and Boevis' post is way more in-depth and micromanaging than the vast majority of feral players will ever achieve, but I'd still love to hear views on the absolute max-dps opening sequence on something like General Vezax or Lord Jaraxx based on this. The problem being in that TF is not on cd and you'd want to use it asap, but not overlap it with Berserk, which is also available - while still not giving the tank early aggro problems in the absence of him using a Speed Potion while running in, or Vigilance et al. Burning Berserk early seems to be a larger issue on progression hard modes when you don't know if getting one more last Berserk will make the difference later on in the fight (given no boss mechanic that calls for reserving Berserk early on, or trying to stack Berserk/Shattering Throw).

Maximizing your utility to the raid probably does not lie in maximizing your own dps. Ergo:
(Assuming very good player timing and no early Clearcasting procs on a hard mode/progression night boss. GCD adds 15 energy as far as I know.)
0. Pop a Potion of Speed as close to, but not before entering Combat, assuming you can rely on not having aggro issues early.
[Enter Combat]
1. FFF unless the boomkin can be relied upon to put it up in the first second of the fight. (Apply while running up, FC to close gap.)
2. Mangle, cost 40 energy - total energy now 60, begin GCD
[1s GCD]
3. SR, cost 25 energy - total energy now 25+, begin GCD
[1s GCD]
4. Rake - absolutely must have SR/Mangle up before Rake, cost 35 energy, total energy now 00 or slightly more, begin GCD.
5. TF is off the GCD but must be pressed after Rake. Energy total now 60+.
[1s GCD]
6. Berserk now, get Hysteria, possibly pull aggro unless you have Vigilance/Hand of Salv?
or
6. Shred, cost 42 energy, total now ~28, begin GCD.
[1s GCD]
7. Shred asap, cost 42 energy, total now ~00, begin GCD.
[1s GCD]
8. if 5CP then Rip asap, cost 30 energy, total now ~00, begin GCD. If not 5CP then 8a.
8a. Shred, cost 42 energy, total now ~00, begin GCD.
[1s GCD]

9. AY, THERE'S THE RUB - You're at low energy, TF still has a few seconds to go and you want Berserk on CD asap so you can maximize the number of them for the duration of the fight, knowing that the last part of the fight will possibly be the most critical, with people dead, a soon-to-be-enraged boss and things falling apart because it's progression night.

Do you wait for the energy to get up to 50-85 and then Berserk?
Do you continue your rotation as per FbN or FaceMauler or your instincts, and Berserk when you have a longer-lasting SR?
Do you Berserk before the first application of Rip (barring boss mechanic that you need to save it for)?
Do you give up on making maximum usage of the first TF buff and just use it as an initial way to get to 100 energy for an early - but inefficiently used - Berserk - i.e., put it in at step (5) above?
Is my timeline above simply way out of whack somehow?

Please keep in mind that I'm only concerned with this issue due to occasionally pulling aggro early on in a hard mode/progression fight where my very-not-hardcore guild is barely able to hope for an eventual win. Being the Hysteria target makes it even more important when and when not to Berserk. Calling for an early Hand of Salv may be the solution, but I don't always get Vigilance, even when we run our normal Warrior tank.

It's such a comically microscopic difference in damage that I can't bring myself to give a damn. Getting that berserk in early with a full energy bar while SR and mangle are up seems more important and quite possibly more overall damage than perfectly using TF but having to refresh mangle or SR during the berserk or waiting too long to use berserk and missing getting a 2nd or 3rd one in. I mean, not saying it's bad to work out the precise timing issues here but more than many things discussed here this seems close to "angels on the heads of pins", ya know?

Point taken, and I think that was sound advice to just not worry about losing the 6-second damage-buff from TF in favour of Berserking early (assuming no threat issues in the absence of Vigilance/Hand of Salv). It's just that we run in to engage bosses so often every week now for years, but up until now I've never really figured out how it should be done. And we've all been in that situation at the end of a very difficult progression fight where Berserk's cooldown is counting down below 20 seconds, the boss is at single-digit percent health and you wipe wondering if you'd just Berserked earlier you might have upped your damage...

Also, thanks much Thendariel for setting me straight. Original post edited to reflect 1s GCD.

When analyzing that 1st berserker (whether to waste TF's 6 second dmg buff or not), you should keep in mind that typical cat has Mjolnir Runestone and DC:G or Death's Choice. Those tend to proc within seconds after entering combat, and with berserker up you can shred away through this time. My experience is that mangle, SR, rake, (potential shred if procs not up), TF, Berserker often matches with these procs. Fortunatelly our guild tanks dont have problem with that.

Maybe i am overseeing something, but why do you compare rip/rake ticks to shred?

As i see it, e.g. in case with rip, you either have free rip (30 energy) or free shred (42 energy). The difference you should compare is 12 energy vs wasted rip tick + wasted combo point.

I personally prioritize mangle, SR and Rip over OOC shred.

edit: Now that i am thinking about it, rake is 40 energy, so i guess there's no reason to prioritize OOC shred over rake?
edit2: My bad, rake is 35, so Shred > Rake.

As far as I understand it, this is about efficient energy usage, not just priority. In the scenario you describe, you get to do both the actions you intend to, since one of them is free and you assume an energy state that requires only one GCD to do the next.

Point (a) is a non-issue, I don't see why you mention it since you can only use OoC for Shred anyway. Even if you did get extremely unlucky and got a 2nd OoC before you used the 1st one, it would still even out with 1-2 wasted CP's, which again translate into energy in the end. For me losing one OoC or wasting 1-2 CP's has more or less the same value energy-wise (2 CP's could be even almost double the value with unlucky crits).

Point (b), I am uncertain as to which is more valuable, 1 second of Rake or 7 free energy points (talented Rake is 35 not 40). I Shred if I can see it in time before I hit Rake.

I would agree with Inaiwae on point (c). You are losing 12 'free' energy, but the energy you would spend to regain 1-2 wasted CP's is at least 36, i.e. a Mangle.

On (d) I agree with you, it becomes even more important if you don't assume that you'll do the Mangle 1 second after Shred, e.g. you are at 15 energy and get an OoC, the 2nd action will be a while longer.

SR Doesn't consume a Clearcast, so if SR needs to be refreshed, you should always do that first, and then use your free Shred. The odds of back to back procs is so low that it's not worth losing a combo point and 33% damage on the Shred. Obviously, if you aren't at 5cp and SR hasn't faded yet, then you should Shred first. The tricky one is if you're at 5cp but SR hasn't faded (Shred probably) or if you're not at 5cp but SR has faded (SR probably).

The math was very old fr the other ones, but wasting a CP and 1 second of Rip uptime was previously shown to be worthwhile (ie. Shred > Rip). Mangle vs Shred comes down to how many bleeders are in the raid. Rake vs Shred is actually quite a bit more difficult, sometimes your cycle is setting up to where you just don't need that 7 energy and that slightly higher uptime on Rake is better.

Mangle increases Shred damage, so i guess in case Shred would land on non-mangled target you always prioritize Mangle.